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Electrical How difficult to build a DIY Lithium Ion Battery Charger?

  1. Sep 27, 2009 #1
    Not asking for a schematic, more a notion of roughly how challenging this will be.
  2. jcsd
  3. Sep 29, 2009 #2
    I read a bit on wikipedia, and it doesn't seem that hard. You charge with a constant current which depends on the battery type until you hit a certain voltage according to the manufacturer's specs around 4.2V per cell, which you hold until there is almost no more current. Does that sound complicated to you? I am sure that there are already ICs available for common Li-battery types.
  4. Sep 29, 2009 #3
    National has a chip. Look up National Semiconductor’s LM3622 Li-Ion
    Battery Charger Controller chip. See also
    http://www.national.com/appbriefs/files/AppBrief101.pdf [Broken]
    for a USB-based lithium ion battery charger circuit.
    Bob S
    Last edited by a moderator: May 4, 2017
  5. Sep 30, 2009 #4
    Interesting thanks. With the chip it seems easy enough.
    Last edited by a moderator: May 4, 2017
  6. Oct 1, 2009 #5
    And I would note that you can buy LI Ion batteries on the internet that have a charging/protection circuit built into the end of the battery (I think they are AA cells) which simplifies charging circuits.
    Last edited by a moderator: May 4, 2017
  7. Oct 2, 2009 #6
    BAAADDD IDEA!!! Charging these beasts is dangerous as it is. I don't mean to be overcautious but I've had one explode in my backyard and it's very dangerous.
  8. Jan 4, 2010 #7
    Charging these batteries is easier than charging NiMh or NiCad's. I think it would be farly straight farward to detect when charging is completed as there is a very noticable change.
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